InterviewSolution
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InterviewSolution
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In Example 3.1. the electron drift speed is estimated to be only a few mm s^(-1) for currents in the range of a few amperes ? How then is current established almost the Instant a circuit is closed ? |
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Answer» Solution :When a BATTERY is connected across a conducting wire, electric FIELD is found to be established in that wire almost with a speed of light. This causes instantaneous local drift of every free electron and that too with a tremendous acceleration because its value given by a = `(eE)/(m)` is found to be very large (becausem being MASS of electron is extremely small equal to `9.1 xx 10^(-31) `kg) Hence all the free electrons start drifting simultaneously which produces instantaneous current in the wire. This current achieves its steady value WITHIN a very short time. (That is why bulb gets on almost at the same moment when we switch it on). |
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